Various films made of resins are used in liquid crystal display devices. Among them, triacetylcellulose is mainly used for a polarizer protection film. A film made of triacetylcellulose has high moisture permeability. Therefore, the quality of a polarizer tends to deteriorate as the thickness of its protection film is reduced. It has been desired to improve the polarizer protection film in the technique of reducing the thickness of a liquid crystal display device.
Therefore, a methacrylic resin has been studied as a new material for a polarizer protection film. It has been known that when a film made of a methacrylic resin is subjected to a stretching process, its tenacity is increased (see Patent Literature 1). However, when an ordinary methacrylic resin film is stretched, its phase difference increases. As a result, in the case of an IPS liquid crystal method, for example, the quality of a picture deteriorates.
It has been known that by adding a polycarbonate resin or the like in the methacrylic resin, a film having a small phase difference can be obtained more easily (Patent Literature 2-5). However, the above-described methacrylic resin compositions have a problem in their stretching property. Therefore, there has been a problem that when a methacrylic resin composition is formed into a thinner film by stretching, it tends to be cracked more easily. Further, when a methacrylic resin composition is stretched at a lower temperature in order to increase the strength of the film obtained by the stretching, the film tends to rupture more easily.